This invention relates to a device for use in venipuncture, i.e., the insertion of a needle into a patient""s vein in order to draw blood, or to carry out an intravenous treatment of some type.
In performing a venipuncture, the nurse, medical technician or other qualified person always seeks to accomplish the task of inserting the needlexe2x80x94in order to draw blood, start intravenous fluids, or inject some medicationxe2x80x94on the first trial. If the first attempt is not successful and another attempt must be made, the patient""s discomfort and anxiety are increased, the chances of infection are increased, and the number of sites available for future venipuncture is further decreased. Hence it is important to make the likelihood of a successful insertion on the first try as great as possible.
In the insertion of a needle into a vein, the needle is positioned directly over the chosen vein at an angle that is selected (1) to avoid pushing the needle completely through the vein and out the opposite side, and (2) to bring the tip of the needle into an appropriate final position so that blood can flow back into the hollow needle, or fluids can flow through the needle into the vein. The vein is surrounded and supported by fatty tissue in the cells that make up the connective tissue, and it lies between the skin and the underlying muscle or bone.
Most persons performing a venipuncture sense the depth of the vein below the skin surface by touch as well as by sight. Another source of information for the person doing the venipuncture is the xe2x80x9cfeelxe2x80x9d of the needle tip as it is inserted in the patient""s arm or other body part. The needle is first pressed through the skin, which is felt as one layer, then through the intervening fatty tissue as a second layer, and finally through the wall of the vein, which is felt as a third layer. The angle at which the needle is inserted may be adjusted as the venipuncture proceeds, and will usually be changed at least in the latter part of the procedure so that the tip of the needle will stay within the vein.
During this procedure any extreme lateral movement of the vein as the needle is being inserted must be avoided. However, the vein is often difficult to hold steady, as it tends to roll, or move sideways, entirely out of the path followed by the needle as the needle is pressed into the tissue above the vein. When this happens, the tip of the needle pushes the vein aside, the venipuncture is unsuccessful, and another attempt to insert the needle in the patient""s vein must be made.
Sometimes the person inserting the needle will try to use his or her fingers to prevent the vein from rolling out of the path of the needle being inserted. This poses the risk of puncturing a finger with the needle, thereby increasing the chance of the operator getting a blood borne disease such as hepatitis B or HIV.
Various complicated, bulky, or cumbersome instruments have been developed for keeping a vein from moving laterally out of the way of the needle as it is being inserted during venipuncture.
U.S. Pat. No. 1,561,116, issued to Silliman on Nov. 10, 1925, discloses a vein stabilizer that has a flat metal plate (or a similar shape formed of wire) for pressing down upon a portion of a distended vein while an immediately adjacent portion of the vein is contained in an opening that is directed towards the heart.
U.S. Pat. No. 1,824,516, issued to Tyvand on Sep. 22, 1931, discloses a vein retainer comprising a complicated plate structure (which carries a pair of adjustable retaining fingers having downwardly turned ends) that is placed over a vein and held there tightly by an adjustable strap. The two fingers carried by the plate press down against the body surface on both sides of a vein for the entire length of the involved portion of the vein, and a third finger (which, extends downwardly from the plate and is positioned transverse to the path of blood flow) pushes down against the vein and restricts the flow of blood so as to distend the vein.
U.S. Pat. No. 2,103,174, issued to Posada on Dec. 21, 1937, discloses a surgical instrument having a plate that comprises a pair of upwardly bowed legs that are connected by spring means to form an opening between the legs, the spring means being manipulable by pressing down separately with the operator""s thumb and index finger applied to the bowed legs in order to narrow the width of the opening that retains the vein, and to confine the vein segment being punctured to cause it to swell up and stand out in bold relief.
U.S. Pat. No. 2,234,961, issued to Canada on Mar. 18, 1941, discloses a mechanism consisting of a tourniquet to which a pivoted metal device is attached. This device has two downsloping legs that can be positioned to press downward at a single narrow location on either side of the vein to be punctured.
U.S. Pat. No. 3,324,854, issued to Weese on Jun. 13, 1967, discloses a vein-stabilizing device that is adapted to be attached to the barrel of a syringe and which includes two leg portions (joined by a connecting member) that initially extend beyond the point of the needle and can be pressed down on both sides of the portion of the vein to be punctured, which causes the connecting member to press down against the vein as well, at a location only a short distance beyond the point at which the needle enters the flesh above the vein.
U.S. Pat. No. 4,314,568, issued to Loving on Feb. 9, 1982, discloses two flat members adjustably hinged (at one end only) to form an opening of variable width between them, with means to lock the members in position to press down on both sides of the vein during venipuncture.
U.S. Pat. No. 4,316,461, issued to Marais et al. on Feb. 23, 1982, discloses a long, flat, rigid rectangular base plate with a medially located opening extending for a part of the length of the plate, and a hood adapted to cover and contact the vein for a part of the length of the opening and exert downward pressure on the vein when the base plate is pressed from above. Once the intravenous needle is introduced. into the vein, the whole assembly is held in place with a pair of straps.
U.S. Pat. No. 4,332,248, issued to DeVitis on Jun. 1, 1982, discloses a device having a parallel pair of downwardly extending leg members for receiving and pressing down around a distended vein, and a third member rigidly positioned with respect to the leg members and adapted to guide a needle at a fixed angle to the vein.
U.S. Pat. No. 4,586,924, issued to Lanning on May 6, 1986, discloses a long, flat plate with a notch at one end which leads to a groove under the plate. When the device is in use, the walls of the groove press down on the vein close to the point of insertion of the needle.
U.S. Pat. No. 5,254,095, issued to Harvey on Oct. 19, 1993, discloses a stabilizer for blood vessels that looks like a shortened, widened forceps and functions similarly. It is formed of two resiliently hinged panels. with their outer edges spaced from each other. Each of the panels has a pair of downwardly extending, narrow legs that taper to thin pointed ends (disclosed as being about the thickness of a slightly dull pencil point) for engaging, and pushing inwardly when the device is manually manipulated, against the skin surrounding the vein for the positioning and stabilizing of the vein into which a needle is to be inserted.
U.S. Pat. No. 5,415,647, issued to Pisarik on May 16, 1995, discloses a vascular immobilizer consisting of a flexible, flat, elongated piece of a clear plastic or plastic-like material with a plurality of grooves on its bottom surface arranged parallel to each other and perpendicular to the longitudinal axis of the device, the grooves being of various calibers and having walls arranged at various angles to squeeze and immobilize a substantial length of the vein in the area into which the needle is to be inserted.
None of these many prior patents which are addressed to problems inherent in a venipuncture procedure discloses or suggests the venipuncture assistor of the present invention.
The venipuncture assistor of this invention is employed to keep a selected segment of a patient""s vein from moving laterally out of the path of a needle that is being inserted in the selected vein segment after the flow of blood in the vein has been restricted by application of a tourniquet or similar device at a location spaced from the intended point of insertion of the needle.
In its broadest form, the device of this invention includes (1) a first substantially rigid arch configured and dimensioned to receive one of the end portions of the distended selected vein segment and associated skin and tissue in which a needle is to be inserted, and (2) a second, similarly configured and dimensioned, substantially rigid arch spaced from and facing the first arch. The arches should be parallel to each other in the horizontal plane, but need not be parallel in the vertical plane. The arches are preferably spaced from each other by a distance approximately equal to the length of vein segment that is customarily steadied, by a person skilled in venipuncture, to receive a needle during venipuncture.
As used in this specification and the accompanying claims, the term xe2x80x9carchxe2x80x9d includes structures that have an overall semi-circular shape, an inverted xe2x80x9cUxe2x80x9d shape, an inverted xe2x80x9cVxe2x80x9d shape or any other suitable shape. Because each arch is substantially rigid, it will be understood that the space spanned by each of said first and second arches is substantially constant in size under any pressure that is exerted on the arches during normal use of the assistor.
At least one support member which has a downwardly facing bottom surface fixedly and substantially rigidly interconnects the two arches. Each of the arches has (1) a lower portion on each side thereof, each of which lower portions has a bottom edge and a generally vertical inner edge that faces inward into the space spanned by the arch, and (2) an upper-portion which has a downwardly facing bottom edge.
The bottom edges and inwardly facing, generally vertical edges of the base portions of the arches and the bottom surface of the at least one support member are free of any exposed sharp-protuberances. It will be understood that the term xe2x80x9cexposed,xe2x80x9d when used in this specification or the appended claims to modify xe2x80x9csharp protuberances,xe2x80x9d refers to such protuberances that are located in positions to press against either the distended selected vein segment and its associated skin and tissue, or against the surrounding surface of the patient""s body part in which the needle is being inserted. Several suitable shapes of the at least one support member are disclosed herein.
The space between the two arches must be substantially free of any member that pressesxe2x80x94when the vein segment and its associated skin and tissue have become distended, because of the restriction of the flow of blood, to a given width, and to a given height above the surrounding surface of the body part in which said needle is being inserted and the assistor is in operative position over the vein that is to be puncturedxe2x80x94against any part of the distended vein segment and associated skin and tissue. In other words, the space between the two arches constitutes a vein-accommodating space.
The invention is first disclosed in this specification, and defined in the accompanying claims, in its broadest form. In this form there is no reference to the fit between the arches and the selected vein segment and its associated skin and tissue after they have become distended, because of the restriction of the flow of blood, to a given width and to a given height. (When used in this specification and the accompanying claims, the term xe2x80x9cassociated skin and tissuexe2x80x9d means the skin and tissue immediately above and immediately adjacent the selected vein segment. As used herein, the xe2x80x9cgiven widthxe2x80x9d is measured at the level of the surrounding surface of the body part in which the needle is being inserted, and the xe2x80x9cgiven heightxe2x80x9d is the height above that same surface.)
The invention is also disclosed and claimed with respect to the given width and given height just mentioned. As thus disclosed and defined, each of the two arches is configured and dimensioned to receive the end portion of the distended selected vein segment and associated skin and tissue that is adjacent the arch with an operative fit measured in the horizontal direction.
In an xe2x80x9coperative fitxe2x80x9d for the purposes of venipuncture, the distended vein segment and associated skin and tissue are neither too loosely nor too tightly confined in the horizontal direction by the arches of the assistor. If the horizontal fit with the arches is too loose the vein segment may not be prevented from moving out of the path of the needle, and if it is too tight there will not be enough room to insert the needle without running the risk of damaging the vein.
Good results are obtained if the fit, measured in the horizontal direction, is between a moderately loose fit and a slightly compressive fit. It is preferred that the width of the arch at its bottom be approximately equal to the given width of the distended vein segment and associated skin and tissue, thereby producing what is referred to herein as a close fit.
(The term xe2x80x9cmoderately loose fitxe2x80x9d is used in this specification and in the accompanying claims to mean a fit that leaves space on each side no greater than approximately 20 percent of the given width of the distended vein segment and associated skin and tissue. The term xe2x80x9cslightly compressive fitxe2x80x9d as used herein means a fit that will reduce the horizontal dimension of the vein segment and associated skin and tissue from their given distended width by no more than about 20 percent.)
The downwardly facing bottom edge of the upper portion of each arch is at least as high as the given height of the distended vein segment and associated skin and tissue, and preferably somewhat higher. As will be seen, the result is that the edge in question does not press against the distended selected vein segment and its associated skin and tissue.
The arches are preferably spaced from each other by a distance approximately equal to the length of vein segment that is customarily steadied, by a person skilled in venipuncture, to receive a needle during venipuncture.
As mentioned above, at least one support member fixedly and substantially rigidly interconnects the two arches. If there are two such support members, one can suitably be positioned on each side of the assistor. Each support member may include two laterally extending members, with a cross-piece fixedly attached thereto and spaced from the inside edge of the base of each of the arches. The assistor may include a brace extending from the top portion of one of the arches to the top portion of the other arch.
If desired, various arrangements of panels, preferably formed of a transparent material such as plastic, may be employed as the at least one support member fixedly and substantially rigidly interconnecting the two arches.
Preferred embodiments of the venipuncture assistor of this invention include a pair of substantially rigid, spaced, opposing end walls and a pair of substantially rigid, spaced, opposing side walls fixedly and substantially rigidly connecting the respective side edges of the end walls. All of these walls are formed in major partxe2x80x94and preferably entirelyxe2x80x94of a transparent material such as plastic. The walls may be planar or curved, as desired. The opposing end walls are preferably spaced from each other at their lateral midsections a distance approximately equal to the length of vein segment that is customarily steadied, by a person skilled in venipuncture, to receive a needle during venipuncture.
In these embodiments, the bottom edge of the lateral midsection of each end wall contains a notch that is configured and dimensioned to receive, with an operative fit measured in the horizontal direction, the distended vein and associated skin and tissue into which a needle is to be inserted. Good results are obtained if the fit, measured in the horizontal direction, is. between a moderately loose fit and a slightly compressive fit. It is preferred that the fit be a close fit, with the width of the notch being approximately equal to the given width of the distended vein segment and associated skin and tissue.
The portions of the end walls that define these notches correspond to the arches in the broadest form of this device that is discussed above. As used in this specification and the accompanying claims, the term xe2x80x9cnotchxe2x80x9d includes (1) openings having an overall semi-circular shape, (2) openings portions of which are curved and portions. of which are are straight such as openings having the shape of an inverted xe2x80x9cU,xe2x80x9d (3) openings having the shape of an inverted xe2x80x9cVxe2x80x9d and (4) openings having any other suitable shape.
Each of the notches is at least as high as the given height of the distended vein and associated skin and tissue, and preferably somewhat higher. As a result, the downwardly facing edge of the upper portion of the notch does not press upon the distended selected vein segment and its associated skin and tissue.
To take advantage of the economy of size provided by this invention, the end walls may suitably be spaced from each other at their lateral midsections by a distance of about 10 mm. to about 30 mm., and the side walls may be similarly spaced from each other by about 10 mm. to about 40 mm. Improved and preferred spacings are discussed below.
The major portion of the bottom edges of the end walls and side walls of these embodiments, taken together, constitutes the lowermost part of the assistor, which is located either (1). in a substantially horizontal plane or (2) in a substantially horizontally disposed portion of a cylindrical surface (a) that has a circular cross section, measured transverse to the involved vein segment, and (b) whose central axis is parallel to, and is positioned a substantial distance below, a straight line that passes through the center of the bottom boundary of each of the notches in the end walls or (3) in a generally planar surface that has a wavy cross section.
The bottom edge of each end wall and side wall of these embodiments may, if desired, be grainy, or vertically wavy, or any other appropriate shape or texture that does not cause the patient discomfort when the venipuncture assistor is pressed downward against the surface of the body part into which the needle is to be inserted. In any case, the bottom edges are free of any exposed sharp protuberances.
It is preferred that, except for the notch in each end wall, the bottom edges of the end walls and side walls in these embodiments extend substantially continuously around the perimeter of the space enclosed by the walls, and in every case these edges extend at least around the major part of that perimeter. In a particularly preferred embodiment, the end walls and side walls form a cylindrical surface and are capped with a substantially flat circular top wall. Other suitable shapes may be used.
For ease of handling and to hold the device in place above the vein in which the needle is to be inserted, the bottom portions of the side walls may be attached to strips of material, preferably adhesive tape, extending laterally on both sides of the device. In a preferred form, the bottom portions of the end walls and side walls of the inverted chamber extend approximately xc2xd mm. to about 1xc2xd mm. below the strips that extend outwardly on both sides of the device.
All forms of the assistor of this invention are preferably made entirely of plastic, in order to make the vein being punctured completely visible as the needle is inserted in the vein.
The venipuncture assistor of this invention is small and uncomplicated in structure, which makes it easy to manufacture and easy to handle and use. It will greatly aid medical personnel in successfully drawing blood from a patient for sending to a laboratory, or inserting a needle into a patient""s vein for the purpose of some intravenous treatment. Because of its structure, it can be immediately and effectively used by a nurse, a medical technician or any other qualified person, without any special training in use of the device being necessary.
The device of this invention is especially useful for inserting a needle into the smaller veins on the arm, a vein that curves near the round part of the wrist, or a smaller vein on the back of the hand. It will also be very useful when a patient""s larger veins have been repeatedly pierced over a long period of time, and smaller veins must be selected for venipuncture. It will enable the person inserting the needle, even one of lesser skill, to perform venipuncture better on a difficult patient such as an elderly person, someone who is emaciated or obese, a patient in shock, or perhaps a child.
Because with this assistor the constriction of the vein to distend the same and the steadying of a vein segment are accomplished separately, it is not necessary to squeeze or bunch the patient""s flesh. Use of the device produces no discomfort or pain on the patient""s part, both because of the absence of pinching or bunching just mentioned and because of the absence of legs or prongs or sharp protuberances that poke into the patient""s flesh.
Because of the round shape of the bottom edge of the inverted cylindrical chamber in a preferred embodiment of the device, the assistor of this invention is to an extent similar to the shape of the surface of the surrounding body part. This increases the effectiveness of the device in holding the surfaces on both sides of the vein segment taut, so that the notches at both ends of the device can better stabilize the vein as the needle is inserted.
One of the most important advantages of this invention is that the assistor can be held in place by downward pressure from one or more of the five fingers of one of the two hands of the person performing the venipuncture, and at the same time another of the five fingers of that hand can be extended to contact a side surface, or the bottom surface, of the body part in which the vein being punctured is located. This means that the latter finger can be braced against the body part to help stabilize the assistor and help the operator maintain his or her balance with respect to the patient.
Whatever the basic shape of the device may be, the short distance between the spaced arches or the notched end walls (in whatever terms the device is described) means that an a suitable length of the vein can be isolated and steadied even if the involved vein portion in its unrestrained condition is somewhat curved in its horizontal outline.
The present invention recognizes the fact that it is not necessary in venipuncture to immobilize the distended vein segment completely. It is sufficient if the vein segment into which a needle is being inserted is kept from rolling sidewise so far and so quickly that it becomes difficult to make the insertion. Sidewise movements up to approximately 1 mm. in either direction (somewhat less with smaller veins) can ordinarily be dealt with successfully by the person performing the venipuncture. It is only necessary that the vein segment to be punctured be kept by the assistor within-a practicable range for insertion of the needle.
This degree of horizontal confinement may be accomplished in all forms of the device of the present invention by providing an operative fit between the two notches or arches of the device and the distended vein segment and associated skin and tissue that are to be punctured.
In the preferred embodiments of the device, the desired degree of horizontal confinement is additionally accomplished by restraining the distended vein segment and associated skin and tissue at only two locations. These locations are strictly limited to the areas within the confines of each arch or notch described above, and exclude the entire space between opposing arches or notches.
Two facts make it possible in these preferred embodiments of the invention to achieve the desired degree of horizontal containment of the vein segment through restraints applied only at the indicated two locations. First, restriction of the flow of blood in the vein to be punctured, by application of a tourniquet or similar device at a location spaced from the intended point of insertion of the needle, produces a distended vein segment and associated skin and tissue that are significantly less flexible than when the vein is in its normal condition. Second, this increased rigidity is especially noticeable when the vein segment being restricted is as short as the selected vein segment customarily is in venipuncture.
In addition to these two facts, in those preferred embodiments of the invention that include geometric shapes whose bottom edges are pressed downward against the body surface outward of the vein segment and associated skin and tissue that are being punctured, the resulting contact tends to cause the patient""s skin on either side of the vein segment to remain relatively taut, which in turn helps to hold the vein segment steady.